As the market for liquid crystal displays (LCDs) has expanded in recent years, there has been a continuing need for high-quality display devices. Further, as liquid crystal display devices have rapidly increased in size, there has been a growing need for high productivity manufacture of liquid crystal display devices for alignment layers. Under these circumstances, there is a continuously growing demand for high-performance materials sufficient to meet different requirements of various types of liquid crystal display devices that produce few defects in manufacturing processes and have excellent electro-optical properties and high reliability. Particularly, the alignment and electrical properties of liquid crystal molecules depending on the characteristics of liquid crystal alignment layers have a great influence on the image quality of LCDs using the liquid crystal alignment layers. In response to high display definition of LCDs, the requirements for the characteristics of alignment layers are becoming more stringent.
Active developments on all plastic displays (AODs) are being made nowadays. In a typical all plastic display, an aligning agent is coated on a low surface tension organic material. Thus, conventional LCD manufacturing processes require the use of aligning agents that exhibit better printability and faster curing at lower temperature as well as better electro-optical properties to improve the quality of LCDs. Since conventional polyimide-based aligning agents have low solubility, large amounts of low surface tension non-solvents cannot be introduced to improve the printability of the aligning agents.
It is known that the characteristics of alignment layers developed hitherto are greatly affected by the structures and characteristics of dianhydrides as monomers of materials for the alignment layers (Japanese Patent Nos. 2743460 and 3322089).